This study is looking at dose response of the 5-HT3 inhibiter dolasetron as an antiemetic against nausea and vomiting induced by chemotherapy with either cyclophosphamide and/or doxorubicin. All patients receive active drug, however, they are randomly assigned to receive 25, 50, 100 or 200 mg p.o. as a single dose prior to chemotherapy with these agents. Patients are followed with serial chemistries and EKG's, and have blood drawn at 0, 2, 4, 8, and 24 hrs after the start of chemotherapy for pharmacokinetic studies of dolasetron.